From an editorial of the same title by William Falk in a recent issue of The Week magazine:

It seems absurd on its face: The U.S. and Britain are the worst places for children to grow up in the Western world. UNICEF came to this off-putting conclusion after surveying 21 developed nations on such measuring sticks as kids' relationships with peers, time spent with parents, drinking and drug use, and finally, the kids' own assessment of their happiness. The most secure and happiest nations for kids, the report card found, are the tightknit societies of the Netherlands, Sweden, Denmark, and Finland; the U.S. ranked next-to-last, and the U.K., last.

...UNICEF's main thesis is hardly controversial: that stable, supportive family and social relationships are far more important to kids' well-being than how much expensive junk they have piled up in their rooms.

Here's a link to a LA Times article about the same survey.